There is a wide variety of scientific operations in which low-cost and accurate temperature control is involved and preferable.
An example of such operations is PCR (polymerase chain reaction). PCR is a technique used in molecular biology to amplify a portion of DNA (Deoxyribonucleic acid) or RNA (after reverse transcription to DNA). In a PCR reaction, the enzyme DNA polymerase generates copies of target sequence in an exponential fashion. Primers are used to amplify specific sequences and nucleotides are added as material which is assembled by polymerase to make DNA copies.
In order to obtain accurate results, rapid thermal cycling is used for fast PCR reactions. However, a time of reaction is typically limited by heating and cooling rates available in instruments. One of the fastest rates has been achieved by liquid flowing across a conducting substrate or a conductive material in contact with the substrate. However, this involves external pumps and complete liquid cooling and heating loops if the system is to be independent/portable. The fluid temperature is controlled accurately to a set point and this implies tight specifications of related control systems and therefore design complexities and higher costs.
Solutions based on Peltier coolers are expensive and power hungry. Systems using TEC's (thermo electric coolers) suffer from reliability issues. As a result of going through thousands of cycles, TEC's may suffer from damages that would make them non-functional.
There are instances where the instrumentation has to be robust, low power or prone to environmental stress like vibration etc. In this case designs similar to normal bench top instruments are not feasible. Complex designs for this purpose are difficult to adopt in a low cost setting like portable diagnostic equipment or Point of Care (POC) instruments.